@article {038_Thorium,
	title = {Thorium partitioning in Greek industrial bauxite investigated by synchrotron radiation and laser-ablation techniques},
	journal = {Nucl. Instrum. Meth. Phys. Res. B},
	volume = {269},
	number = {24},
	year = {2011},
	pages = {3067 {\textendash} 3073},
	abstract = {Typical red{\textendash}brown (Fe-rich) and high-quality white{\textendash}grey (Fe-depleted) bauxite samples from active mines of the Parnassos-Ghiona area, central Greece, were investigated. According to \{XRF\} and ICP-MS analyses their actinide content, and particularly of Th, is relatively increased. Fe-depleted samples contain up to 62.75\&$\#$xa0;ppm Th corresponding to 220\&$\#$xa0;Bq/kg due to 228Ac (232Th-series), whereas Fe-rich samples are less Th-radioactive (up to 58.25\&$\#$xa0;ppm Th, 180\&$\#$xa0;Bq/kg due to 228Ac). Powder-XRD patterns showed that Th-enriched (Fe-depleted) bauxite consists mostly of diaspore (AlOOH polymorph), anatase and rutile (TiO2 polymorphs). SEM-EDS indicated the presence of Ti{\textendash}Fe{\textendash}containing phases (e.g. ilmenite, FeTiO3), chromite (Cr-spinel) and besides LREE-minerals (mostly bastn{\"a}site/parisite-group) and zircon (ZrSiO4) hosting a part of the bulk Th. The presence of Th in diaspore and in Ti-containing phases (not detected by SEM-EDS as in the case of REE-minerals and zircon) was investigated, into distinct pisoliths of Fe-depleted bauxite, using μ-XRF and μ-XAFS in the SUL-X beamline of the \{ANKA\} Synchrotron facility (KIT, Germany). \{XAFS\} spectra of Th salts and Th-containing reference materials were obtained as well. Accordingly it was revealed, for the first time in the literature, that Ti-phases, and particularly anatase, host significant amounts of Th. This novel conclusion was complementary supported by LA-ICP-MS analyses indicated an average of 73\&$\#$xa0;ppm Th in anatase grains together with abundant Nb (3356\&$\#$xa0;ppm), Ta (247\&$\#$xa0;ppm) and U (33\&$\#$xa0;ppm). The Th LIII-edge \{XAFS\} spectra as compared to reference materials, give also evidence that Th4+ may not replace Ti4+ in distorted [TiO6] fundamental octahedral units of anatase and ilmenite lattice (CN\&$\#$xa0;=\&$\#$xa0;6). The occupation of either extraframework sites of higher coordination (CN\&$\#$xa0;=\&$\#$xa0;6.9 or even CN\&$\#$xa0;=\&$\#$xa0;7.4), according to \{EXAFS\} signals evaluation, or of defected/vacant (**) sites is more probable. This is likely explained by the difficulty of Th4+ to replace directly Ti4+ in [6]-coordinated (octahedral) sites due to the large difference in the relevant ionic radii (0.940 and 0.605\&$\#$xa0;{\r A} respectively).},
	keywords = {Bauxite},
	issn = {0168-583X},
	doi = {10.1016/j.nimb.2011.04.061},
	author = {Gamaletsos, P. and Godelitsas, A. and Mertzimekis, T. J. and G{\"o}ttlicher, J. and R. Steininger and Xanthos, S and J. Berndt and S. Klemme and A. Kuzmin and G. B{\'a}rdossy}
}
